1. The Field of the Invention
This invention relates to hand tools and, more particularly, to novel systems and methods for constructing, applying, and using grips for applying torque to tool handles.
2. The Background Art
Hand tools are still a part of the daily life of many professionals as well as home users. Hand tools come in a variety of shapes, sizes, purposes, and constructions. Tools are a part of every job performed by every person in the world. Tools may include computers, machine tools, power tools, automated tools, hand tools, needles, papers, files, and so forth. Tools of an individual's trade may be interpreted to mean those "things" that a person requires in order to work, work more efficiently, and the like.
Tools that are adapted to apply energy to a workpiece may be thought of as traditional tools. For example, hammers, saws, screwdrivers, wrenches, chisels, and the like are common hand tools. Every profession relying on hand work may have an assortment of available tools.
Power tools may be thought of as tools requiring a power source in addition to a human user, which power source drives some element of the tool. For example, power saws, pneumatic nail drivers, staplers, drills, power screwdrivers, impact wrenches, and so forth, are all examples of power tools that may be free-standing or portable. Tools may be held by a user or merely guided or controlled by a user.
Whenever a user of any tool is required to maintain a grip on the tool in order to effect its use, risks arise. Risks may involve improper functioning of a tool. Risks may involve improper guidance, control, or skill in using a tool. Many risks associated with tools may relate directly to a user's ability to maintain a secure grip on a handle or handle portion of a tool of any variety. Control of the tool, safety of the tool, safety of users and bystanders from damage inflicted by a tool, effective operation of a tool on a workpiece, and protection of a workpiece from damage due to failure of control of a tool, may all be dependent upon the quality of control that may be exerted by a user on a handle of a tool.
Tool handles have been the subject of developments since time immemorial. The shape of many handles on work tools, weapons, game tools (racquets, bats, etc.), as well as a host of other "tools" have handles adapted to the nature of the use of the tool and the nature of the grip of a user applied to the handle of the tool.
Several major difficulties arise in practice with respect to tools and tool handles. Fatigue plagues every user of a tool. Long use, the rigidity and shape, and other factors relating to handles may affect the level of fatigue experienced by a user required to grip a handle of a tool. Likewise, a user may sweat according to a level of exertion or environmental temperature and the like. Moisture between a hand of a user and a handle of a tool reduces the friction available between the surface of the hand and the surface of the handle.
What is needed is an improved grip that may be universally applied to tool handles in a variety of tools. By tools may be included all implements having a handle or handle portion that should or must be gripped by a user for proper control or operation. Thus, a tennis racquet is a tool, as is a golf club. Moreover, a hand screwdriver, or a hammer is a tool as is a power saw, power drill, impact wrench, and so forth.
Two of the most difficult circumstances for controlling a tool involve application of torque and thrust. Torque may be thought of as rotating a handle or handle portion, typically using a wrist flexure to rotate circumferentially in the direction of fingers wrapped around a handle.
Thrust may be thought of as urging a handle in a longitudinal direction such as across the palm of the hand of user, transverse to fingers wrapped around a handle. Typically, a motion of an arm or forearm may be used. In thrusting a tool, full body weight, shoulder strength, and the like may be applied to a handle of a tool through a hand of a user gripping the tool. One may understand that the grip of a hand of a user applied to a tool handle is critical. If a tool handle has a smooth surface, the grip in torsion or thrust is controlled by the coefficient of friction, normal force, and resulting frictional force applied by a user.
Various mechanisms have been implemented to improve the ability of a user to grip a handle effectively. Contouring a handle to fit on and around fingers is a classical example of attempting to overcome the limitations of friction between a hand of a user and a handle of a tool. Adhesives and other tacky or sticky materials have been applied to handles as well. Applying chalk and other dehydrating materials to handles is another mechanism used to improve the effective grip of a user on a handle.
User comfort affects the ability to operate a tool without pain, as well as the ability to operate a tool with a minimum of fatigue. As a practical matter, user comfort in securely holding a handle is a matter of substantial concern to virtually all manufacturers of tools (e.g. toys, sporting equipment, work tools, hand tools, power tools, etc.).
One approach to comfort is contouring the shape of a handle to fit a user, however, users come in different sizes. Tools are also used in a variety of positions. A single, solid, contoured surface is effective to some extent. However, in the application of many tools to a workpiece, contoured grips are not universally effective.
Another approach to improving user comfort in order to reduce fatigue involves padding. Leather, plant fibers, synthetic materials, and the like have been added to absorb moisture from a hand of a user, distribute stress over the skin surface of a user gripping the handle and so forth.
Each method for providing a comfortable gripping surface for a user may provide certain benefits with certain costs, and often specific limitations. For example, leather may eventually become slippery. Cleaning leather is problematic. Knurling is expensive and actually produces great localized stress and discomfort to the hand of a user with extended use, and synthetics have proven to be largely ineffective in many applications.
For example, plastic is not so cold as steel in cold environments nor as hot in hot environments. Moreover, plastics may be lighter than metals and less expensive. Rubber and other elastomeric materials, whether natural or synthetic are problematic when formed as continuous solid materials. Typically, elastomeric materials are somewhat improved over rigid materials such as metals and hard plastics, but eventually fail to maintain grip capacity when moistened. Resilience may be adequate for durability but engagement by a user is typically inadequate. That is, elastomeric materials are usually too stiff if solid and too soft if expanded.
Alternatively, urethane foams have been used in recent years. Urethane foams may improve comfort. However, the stiffness of foam materials applied to handles today is typically only for comfort and distribution of stress in a normal direction with respect to the surface of a hand user or the surface of a tool handle. It is usually completely inadequate for applying a torque effectively and is not designed to do so. Expanded polymeric materials, particular expanded elastomeric polymers, typically have a sufficiently high void fraction and a significantly small modulous of the elasticity, that torque applied to handle can completely reduce the expanded material to a size limited only by conservation- of-mass principles.
What is needed is a grip adaptable to a variety of handles of tools. The grip needs to provide a comparatively high void fraction and a comparatively high stiffness as compared with conventional urethane foams used in exercise equipment, tools, and the like. The grip needs to be shaped suitably for achieving excellent torque and thrust properties even without specialized shaping, such as contouring, to the hand of a user or providing barriers in a direction of motion or force (like the thumb rest or hilt on a screwdriver, for example) a material needs to be considerably more durable than conventional elastomeric materials such as dipped vinyls, urethane foams, and the like, which can be easily torn, separated from the tool handle, or reduced to ineffectiveness by application of the forces which a user is capable and desirous of delivering to a workpiece.